Increasing emphasis on higher mileage in vehicles has in turn led to more highly curved and aerodynamic windshields. It is more difficult for the wiper arm to conform as the wiper blade is swept across a highly curved windshield, as compared to a flatter surface. Beyond the conformation problem, there is the problem of the variation in the wiping pressure of the of the wiper blade against the glass. Typically, the wiper arm consists of a base, which is fixed to the oscillating post of the wiper drive mechanism, and a blade mounting portion, which is pivoted to the base. Wiping pressure is exerted on the blade by a long tension spring hooked between the base and the mounting portion. As the arm wipes over the curved windshield surface, it and the blade mounting portion of the arm rise and fall relative to the base. Consequently, the spring will expand and contract, and the wiping pressure varies. A compromise value for the wiping pressure has to be tolerated, higher at some points in the wipe pattern, lower at others. Other, although less common, wiper arms have a one piece design and are cantilevered from the post, or from a base fixed to the post. In cantilevered arms, the wiping pressure results from the deflection of the arm itself relative to the base, rather than from a separate spring. The same problem still exists, however, because the deflection of the arm will also increase and decrease as the arm deflects.